Scottsdale Police spokesman Kevin Watts said that Hezron Parks turned himself in on Sunday after seeing reports about the shooting death of Tempe Fire Department Capt. Kyle Brayer, 34.

Kyle BrayerTempe Fire Medical Rescue Department

Brayer, an ex-marine who had been with the department for 10 years, was in the back of a golf cart driving in downtown Scottsdale when a red Scion began bumping the vehicle, police said.

Brayer approached the car and was shot in the head, police said. The driver fled, slamming into other cars as he sped away.

Hezron ParksScottsdale Police Department

Citing court documents, NBC affiliate KPNX reported that Parks said Brayer yelled at him and kicked his car. Parks claimed felt threatened as Brayer moved toward him, the documents say, so he reached for his gun and fired — though he didn’t know a bullet was in its chamber.